The present invention relates to medical tools that assist in orthopedic, and in particular spinal, surgical procedures. More particularly, the invention relates to tools that may be easily and safely inserted and removed from spaces between joints or prostheses, or between adjacent bone structures, and to tools that assist in the insertion or removal of other tools or devices from locations within joints or prostheses, or between adjacent bone structures.
Advancing age, as well as injuries, can lead to changes in the various bones, discs, joints and ligaments of the body. In particular, these changes can manifest themselves in the form of damage or degeneration of an intervertebral disc, the result of which is mild to severe chronic back pain. Intervertebral discs serve as xe2x80x9cshockxe2x80x9d absorbers for the spinal column, absorbing pressure delivered to the spinal column. Additionally, they maintain the proper anatomical separation between two adjacent vertebra. This separation is necessary for allowing both the afferent and efferent nerves to exit and enter, respectively, the spinal column.
Treatment for a diseased or damaged disc can involve the removal of the affected disc and subsequent fusion of the opposing vertebra to one another. Spinal fusion consists of fusing the adjacent vertebrae through the disc space (the space previously occupied by the spinal disc interposed between the adjacent vertebral bodies). Typically, a fusion cage and/or bone graft is placed into the disc space to position the vertebrae apart so as to create more space for the nerves, to restore the angular relationship between the adjacent vertebrae to be fused, and to provide for material that can participate in and promote the fusion process.
Several different tools have been developed to facilitate the preparation of the adjacent vertebral bodies, as well as the subsequent placement and/or removal of an implant between adjacent bone structures. Typically, prior to insertion of an implant, bone preparation tools are used to prepare the bone surfaces of the adjacent vertebrae. Mallets are often used to apply an impacting force on a medical tool, such as a chisel, to remove bone from a vertebral body. Mallets are also commonly used to insert an implant, and to remove tools positioned between adjacent vertebrae. While mallets are effective, the impacting force must be axially applied to avoid misalignment of the prosthesis, or the inadvertent removal of bone. Moreover, the force applied must be sufficiently accurate to avoid damage to the vertebrae.
To overcome some of these problems, slap hammers have been developed and are widely used in orthopedic procedures to apply an impacting force on various tools used during surgery. However, most slap hammer designs still have several drawbacks. Current slap hammers are typically only used for removal of medical devices and tools, and tend to be very large and heavy, and are thus difficult to handle. Exceptional care must be exercised while using these instruments to prevent injury to the patient and/or the surgeon. In particular, the surgeon""s hands can be pinched between the hammer portion of the instrument and the hammer stops. Care must also be exercised to prevent accidental disengagement of the slap hammer from the device.
Accordingly, there remains a need for an improved slap hammer device which can be safely and effectively used to apply both an insertion and removal force to a medical tool.
The present invention pertains to a force applying surgical system which includes a medical impacting device and a surgical tool. The medical impacting device can be selectively mated with a variety of surgical tools, and is effective to enable a surgeon to provide a force in a desired direction to either insert or remove the associated surgical tool (or a device attached to the tool) from an orthopedic structure. The medical impacting device is a slidable mass which can engage the surgical tool in a removable, replaceable manner. This medical impacting device can be selectively reciprocated along an axis of the surgical tool.
In one embodiment, a surgical system is provided including an elongate surgical tool having a handle portion and a distal portion extending therefrom, and a substantially cylindrical impacting device, e.g. a hollow slidable mass, removably and replaceably disposed around the handle portion of the surgical tool. The slidable mass includes a proximal end, a substantially open distal end, and a side wall extending therebetween and defining an inner lumen. The side wall includes a longitudinally extending opening formed therein and in communication with the inner lumen. In use, the slidable mass is rotatably movable between a first orientation, in which the mass is slidably and operably mated to the surgical tool, and a second orientation in which the mass is removable from the surgical tool. When the mass is positioned in the first orientation, the mass can be slidably moved along a longitudinal axis of the surgical tool to apply a force to the tool.
In another embodiment, the handle portion of the surgical tool includes a proximal end, a distal end, and four sides extending therebetween. A first pair of opposed sides can have a first shape, and the other pair of opposed sides can have a second shape. The first shape of the first pair of opposed sides can be, for example, substantially flat, and the second shape of the other two opposed sides can be, for example, substantially rounded. The opening in the side wall of the mass can have a shape complementary to the first shape of the two opposed sides of the handle to allow the handle to be disposed around the mass. In a preferred embodiment, the two opposed, substantially flat sides have a first width, the other two opposed substantially rounded sides have a second width, and the width of the groove is greater than the first width, and less than the second width.
The groove or opening in the sidewall of the mass is useful in that it allows access to the hollow inner portion of the impacting device, enabling a surgical tool to be mated with the impacting device. A tool suitable for mating with the impacting device is one in which the handles of the tool will fit within the groove in a first orientation, but not in second orientation. Once the tool is mated with the impacting device, the tool is rotated 90xc2x0 to a locked position to prevent removal of the tool through the groove. While in the locked position the impacting device is able to be manually reciprocated along the longitudinal axis of the tool.
The slidable mass is used to insert the tool (or an attached device) within an orthopedic structure, or remove the tool (or an attached device) from within an orthopedic structure by applying a force to the surgical tool. The distal end of the surgical tool may have formed thereon a bone preparation device (e.g., a rasp), a trial device, a connection element that allows the tool to attach to another device, or another surgically useful element. The preparation device and the trial device may be integral with the elongate member or they may be selectively attached to the elongate member through the connection element.
In another embodiment, the proximal end of the slidable mass can include an inner, substantially flattened proximal end wall, and an inner, substantially tapered distal end wall having a central opening extending therethrough. The slidable mass is effective to apply a proximally directed force to the inner, proximal end wall and a distally directed force to the inner, distal end wall. In a preferred embodiment, the slidable mass has a length greater than a length of the handle portion of the surgical tool. The mass is movable between a first proximal position, in which the open distal end of the mass abuts the distal end of the handle portion and the proximal end of the mass is positioned proximal to the proximal end of the handle portion, and a second position, in which the proximal end of the mass abuts the proximal end of the handle portion and the distal end of the mass is positioned distal to the distal end of the handle portion.